Articles manufactured on continuously operating production lines typically are moved from the end of the line to another location remote from the line for further handling. In large manufacturing facilities made up of spaced production lines transportation of the finished products to a warehouse or staging center can be a problem, especially if the product is large and is produced at a rapid rate.
Bulky packages of fiber glass insulation are examples of articles which are difficult to transport from one location to another within a manufacturing facility without creating problems. Because the packages come from the bagger at too fast a rate to allow them to be stacked and moved by a fork lift truck, and because a number of bagging machines are commonly operating at the same time, conveyors have been used to move them to remote locations. Various types of conveyors are available for use. None, however, is ideally suited for the purpose.
Overhead conveyors are commonly used where a clear path to the process equipment is required. They are, however, expensive to support and difficult to service, requiring catwalks and stairs for access. In addition, the equipment required to load overhead conveyors can be prohibitively expensive. Moreover, if material being transported on the conveyor is backed up or blocked, it can fall, thus creating a safety hazard. Also, their height prevents operators from being able to observe products being conveyed along the full length of the conveyors.
Conveyors located under the floor solve many of the problems created by overhead conveyors but create other problems of their own. They are typically very costly and in many cases are not practical to install because of ground water or unstable soil conditions or because it would disturb existing under-floor services. Movement by fork-lift trucks across the trenches resulting from the installation of under-floor conveyors, particularly if the trenches are wide, may require extensive structural bridging. Further, maintenance and housekeeping are difficult in the pits required by under-floor conveyors. Although such conveyors eliminate the need to lift product up to an overhead conveyor, it can be quite costly to lower product onto an under-floor conveyor and to elevate it back up to floor level. In addition, operators also have problems in observing the product being conveyed, and back-up or blockage of product is difficult to clear.
As an alternative to overhead and under-floor conveyors above-floor conveyors are often used. These are typically mounted from 16 inches to 60 inches off the floor, which makes loading and unloading relatively easy depending on the height of the process equipment. Such conveyors are convenient to service and they allow observation of the product being conveyed. Product jams are easy to clear and are not often hazardous. They still, however, restrict access by personnel and fork-lift trucks to and from the process equipment. Installations of above-floor conveyors typically tend to create barriers around the process equipment, allowing no access without bridging over the conveyors.
Still another type of conveyor is the floor conveyor, which is nominally flush with the floor and can thus transport material level with the floor. Examples are people-moving conveyors and conveyors used to handle baggage at airports. Typically, these conveyors are either very complicated devices which include metal decking, wheels and tracks, or are conventional slider bed conveyors which have been sunk into the floor so that the surface of the conveyor is flush with the floor. In either case the floor must be excavated for the full length of the conveyor. They are thus expensive to install and service and cannot be relocated without great additional expense.
It would obviously be desirable to be able to convey articles over relatively long distances in a manner which does not have the drawbacks of the prior art conveyors and which can be installed at an economical cost.